The present invention relates to an apparatus for automatically mounting electronic components to a board, and more particularly to an apparatus which is adapted to insert electronic components having lead wires to holes of a board, cut and fold the lead wires and fix the electronic components to the board.
In a conventional mounting apparatus of the type referred to above, there are arranged a table part for positioning a board at a predetermined position, a feeding part for feeding tape-bonded electronic components having lead wires, an insertion head for separating the electronic components supplied from the feeding part from the tapes and inserting them in to holes of the board, and a fixing head opposed to the insertion head via the board for fixing the electronic components to the board after cutting and folding the lead wires of the inserted electronic components. One AC servo motor is used as a driving source for the insertion head and the fixing head because of a necessity to synchronize both heads. The AC servo motor is connected directly with the insertion head, but connected to the fixing head via timing pulleys and a timing belt to transmit a driving force, thereby driving both heads synchronously. A chain and sprockets, or gears and a transmission shaft, are used in some cases instead of the timing pulleys and the timing belt.
The conventional apparatus will be described with reference to FIG. 4. The apparatus consists of components designated by 33-43. More specifically, in FIG. 4, an electronic component having lead wires is supplied from a feeding part 31 in a tape-bonded state. The electronic component is separated from the tapes before the electronic component is inserted in to a hole of a board 32 by an insertion head 33. A fixing head 34 facing the insertion head 33 via the board 32 cuts and folds the lead wires of the electronic component inserted in to the board, then fixes the electronic component to the board 32. A single driving source, i.e., AC servo motor 35, applies a driving force simultaneously to the insertion head 33 and the fixing head 34. Besides the above-described component parts, the apparatus includes a timing pulley 36 set at an output shaft of the AC servo motor 35, a timing pulley 37 at a driving shaft of the fixing head 34, a timing belt 38 for transmitting a driving force of the timing pulley 36 to the timing pulley 37, a manual handle 39 for bringing rotary encoders connected to the insertion head 33 and the fixing head 34 to origins of the encoders after the apparatus stops, a cam 40 as a part of the insertion head 33, a lever 41 for driving the insertion head 33 in association with the cam 40, a cam 42 as a part of the fixing head 34, and a lever 43 following the cam 42 for driving the fixing head 34.
The above mounting apparatus above operates in the following manner. First, the insertion head 33 is driven by a driving force of the AC servo motor 35. The electronic component is received from the feeding part 31 and inserted in to the hole of the board 32. At the same time this, the driving force of the AC servo motor is transmitted via the timing pulleys 36, 37 and timing belt 38 to drive the fixing head 34. As a result, the lead wires of the electronic component inserted to the hole of the board 32 are cut and folded, and the electronic component is thus fixed to the board 32.
The above constitution necessitates the single driving source to drive both the insertion head 33 and the fixing head 34, generating a large rotational load. The AC servo motor 35 becomes disadvantageously bulky in size. Moreover, a large inertia of the rotational load lengthens the time for activating or stopping the apparatus. Further, distant shafts such as those of the insertion head 33 and fixing head 34 have to be simultaneously driven in an interlocking manner with the use of the transmission component, e.g., the timing belt 38 or the like, causing the apparatus to be complicated in structure. The amount of stroke cannot be changed by an up-down mechanism consisting of the cam 42 and lever 43 in the fixing head 34, and the assembly of the up-down mechanism is hard to adjust, complicated in structure and large in size. Since a lifting part for moving the whole fixing head 34 up and down and a folding part for cutting and folding the lead wires of the electronic components and fixing the electronic components to the board are driven by one driving source, the rotational load is increased to make the driving motor large. The inertia of the rotational load is so large that a long time is required for stopping and starting the apparatus.